Vulnerability report

Active exploitation observed Confirmed confidence In CISA KEV

CVE-2026-82078

PaperCut MF/NG

PaperCut MF/NG · affected before 24.1.10

Watch CVE-2026-82078 Browse KEV feed
Severity
CVSS 9.4 · Critical
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
63.5%
First observed
29 Aug 2026
Last observed
12 Oct 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-82078 is a vulnerability affecting PaperCut MF/NG. An unsafe dynamic class loading vulnerability exists in the database connection utilities of PaperCut MF and PaperCut NG. The application instantiates...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

PaperCut MF/NG affected before 24.1.10.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

An unsafe dynamic class loading vulnerability exists in the database connection utilities of PaperCut MF and PaperCut NG

An unsafe dynamic class loading vulnerability exists in the database connection utilities of PaperCut MF and PaperCut NG. The application instantiates database driver classes based on configurable driver names without validating against an allowlist of approved drivers.

If an attacker can manipulate system configuration parameters, this enables the execution of arbitrary Java bytecode residing on the application classpath under the security context of the PaperCut server process.

PaperCut Affected
PaperCut MF/NG
Before 24.1.10 Before 25.0.13 Before 26.0.5
Published
28 Aug 2026
Exploitation Reported
27 Aug 2026
Attack vector
Remote
Complexity
Low
Privileges
High
User interaction
None

Tags

cisa

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

Previdian

Recorded 27 Aug 2026

Previdian independently recorded this as exploited after first seeing it in honeypot sensors.

Active exploitation observed

Previdian sensor

First observed 20 Aug 2026

Previdian first observed exploitation attempts targeting this vulnerability in our honeypot sensors.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
PaperCut First 2026-08-27 20:32 UTC
Rapid7 2026-08-28 10:09 UTC
Previdian Sensors 2026-08-30 20:11 UTC
CISA 2026-08-31 14:20 UTC
CVE 2026-08-31 15:42 UTC
PaperCut Security Bulletins 2026-09-05 22:30 UTC
watchTowr 2026-10-09 18:20 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Previdian sensors recorded exploitation attempts targeting this vulnerability. The cards and chart show volume, unique attackers, and daily activity.

599

Attempts observed

58

Unique attacker IPs

24

Attacker countries

AZ · BG · BR · DE · DK · ES · FI · FR · GB · HK · ID · IE · IN · KH · MA · NL · PT · RU · SA · SE · SG · TR · TW · US

1

Sensors observed

CVE-2026-82078 exploitation attempts over the last 47 days

Daily events observed by Previdian sensors

Updated 13 Oct 2026

0
7
0
0
6
1
4
1
0
1
11
2
1
0
0
0
0
52
300
10
0
40
0
0
0
0
0
0
0
0
0
10
0
29
10
10
10
10
10
14
10
10
11
12
10
7
0
28 Aug 7 Sep 17 Sep 27 Sep 13 Oct

First observed 29 Aug 2026 · Last observed 12 Oct 2026

Pro adds sensor region and window summaries. Enterprise adds raw IPs, paths, User-Agents, and payloads.

Start 14-day Pro trial

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
554
15
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

Learn about Pro API access

Risk and context

Severity, weaknesses, and research context

CVSS v4.0

9.4 Critical

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

EPSS

63.5%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection') CWE-470

Recent mention · watchTowr

Death By A Thousand PaperCuts (PaperCut Pre-Auth RCE Chain and Patch Bypasses WT-2026-0141-0144/CVE-2026-82077/CVE-2026-82078/CVE-2026-81578)

Before we begin, yes - it's confusing. There are more vulnerabilities with watchTowr IDs in this blog post than there are CVE IDs (assigned by PaperCut), due to PaperCut bundling vulnerabilities and then patch bypasses for those same vulnerabilities into singular CVE...

Read full advisory

All CVSS Scores

CVSS v4.0 9.4 Critical

CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

CVSS v3.1 9.1 Critical

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

All Mentions

Recent mention · watchTowr

Death By A Thousand PaperCuts (PaperCut Pre-Auth RCE Chain and Patch Bypasses WT-2026-0141-0144/CVE-2026-82077/CVE-2026-82078/CVE-2026-81578)

watchTowr · 09 Oct 2026

Before we begin, yes - it's confusing. There are more vulnerabilities with watchTowr IDs in this blog post than there are CVE IDs (assigned by PaperCut), due to PaperCut bundling vulnerabilities and then patch bypasses for those same vulnerabilities into singular CVE IDs.Paper! It still exists.We have

Recent mention · Rapid7

Metasploit Wrap Up: This One Goes to Sixteen!

Rapid7 · 11 Sep 2026

This One Goes to Sixteen!Another banger from Metasploit with sixteen new modules, including ten exploit modules, with five on the CISA KEV list. Cisco, Papercut, Sonicwall, Jetbrains, and Langflow all have exploit modules, and not to be outdone, we even have a Metasploit scanner to watch the watchers!New module content (16)Elasticsearch ingest-attachment Apache Tika XFA XXE Local File ReadAuthors: Bourbon Offensive Security Services and Jean-Marie BourbonType: AuxiliaryPull request: #21739 contributed by kmkzPath: scanner/http/elasticsearch_tika_xfa_xxeCVE...

Recent mention · TheRegister

Hundreds of AI agents helped PaperCut attacker hit 395+ orgs, and some went off script

TheRegister · 10 Sep 2026

Human operator: don't touch CIS orgs. AI agents: look a squirrel!

Recent mention · RecordedFuture

August 2026 CVE Landscape

RecordedFuture · 08 Sep 2026

In August 2026, Insikt Group® identified 73 high-impact vulnerabilities that should be prioritized for remediation, 43 of which had a Very Critical Recorded Future Risk Score. This represents a 14% decrease from last month.

Recent mention · PaperCut Security Bulletins

URGENT Security Advisory: PaperCut NG/MF Security Bulletin (27 Aug 2026)

PaperCut Security Bulletins · 05 Sep 2026

URGENT Security Advisory: PaperCut NG/MF Security Bulletin (27 Aug 2026) THE PAGE APPLIES TO: collapseMenuSize" id="toc-container" class="toc" :class="tocFullyScrolled ? 'toc--bottom' : 'toc--scrolling'" aria-label="Table of Contents"> Contents Overview URGENT Security Advisory Immediate action required Emergency Patch Release 3 Security issues addressed Who is potentially impacted Indicators of compromise and investigation guidance Current Status FAQs Security notifications Updates Contents Overview URGENT Security Advisory Immediate action required Emergency Patch Release 3 Security...

Recent mention · The Hacker News

Attackers Exploit PaperCut Flaws to Steal Credentials From Schools and Universities

The Hacker News · 05 Sep 2026

Threat actors are exploiting the newly disclosed PaperCut flaws to facilitate credential theft in attacks targeting the education sector in the U.S. and Europe. The Arctic Wolf Adversary Research Team said it observed attackers exploiting CVE-2026-81578 and CVE-2026-82078 – an authentication bypass and remote code execution chain – to conduct command execution and reconnaissance, as well as

Recent mention · Rapid7

PaperCut NG/MF Critical Zero-Day Exploited in the Wild

Rapid7 · 28 Aug 2026

Overview On August 27, 2026, PaperCut Software published an urgent security advisory stating that it is investigating active exploitation of a vulnerability affecting PaperCut NG and PaperCut MF. PaperCut has confirmed customer incidents and is treating the issue as a security emergency. At the initial time of disclosure, the vulnerability had not been assigned a CVE identifier, and PaperCut had not publicly disclosed a CVSS score, vulnerability class, authentication requirements, or the technical details of the exploit path. However on August 28, the vendor assigned CVE-2026-81578 and...

Timeline

From disclosure to observed exploitation

  1. 18:20 UTC

    KEV confirmed by watchTowr

    Exploitation attested by an external source

  2. 22:30 UTC

    KEV confirmed by PaperCut Security Bulletins

    Exploitation attested by an external source

  3. 15:42 UTC

    KEV confirmed by CVE

    Exploitation attested by an external source

  4. 14:20 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  5. 15:39 UTC

    CVE ID assigned

    Previously tracked as VULN-2026-0001

  6. 11:45 UTC

    CVE published

    Vulnerability disclosed publicly

  7. 10:09 UTC

    KEV confirmed by Rapid7

    Exploitation attested by an external source

  8. 00:13 UTC

    CVE ID reserved

    Identifier reserved by the CNA

  9. 21:41 UTC

    Added to the Previdian watchlist

    Pro and Enterprise Watch users had 4 days of early warning before CISA KEV.

  10. 20:32 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  11. 11:37 UTC

    Indicators of compromise added (61)

    Indicators of compromise recorded

  12. 11:37 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

Start 14-day Pro trial Read API docs
  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-82078

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2026-82078",
  "confidence": "Confirmed",
  "cvss_score": 9.4,
  "cvss_estimated": false,
  "epss_score": 0.63532,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 599, "sensors": 1 }
}